The polymerizable organic matrix of dental filling composites and adhesives is usually based on a mixture of dimethacrylates (cf. A. Peutzfeldt, Resin composites in dentistry: the monomer systems, Eur. J. Oral. Sci. 105 (1997) 97-116; J. W. Nicolson, H. M. Anstice, The chemistry of modern dental filling materials, J. Chem. Ed. 76 (1999) 1497-1501; J. W. Stansburry, Curing dental resins and composites by photopolymerization, J. Esthet. Dent., 12 (2000) 300-308; N. Moszner, T. Hirt, New Polymer-Chemical Developments in Clinical Dental Polymer Materials: Enamel-Dentin Adhesives and Restorative Composites, J. Polym. Sci. Part A: Polym. Chem. 50 (2012) 4369-4402). Examples of frequently used dimethacrylates are the highly viscous crosslinkers 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA) and 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,4,4-trimethylhexane (UDMA) or the low-viscosity dimethacrylates used as diluting monomers, such as e.g. bis(methacryloyloxymethyl)tricyclo[5.2.1.]decane (TCDMA), decanediol-1,10-dimethacrylate (D3MA) and triethylene glycol dimethacrylate (TEGDMA). Bisacrylamides, such as e.g. N,N′-diethyl-1,3-bis(acrylamido)-propane, which are characterized under aqueous-acid conditions by significantly higher hydrolytic stability compared with dimethacrylates (cf. N. Moszner, U. Salz, J. Zimmermann, Dent. Mater. 21 (2005) 895-910), are also suitable as crosslinkers for aqueous adhesives.
Monomers which contain two different polymerizable groups are called hybrid monomers. EP 0 792 882 A1 discloses dental materials which contain polymerizable hybrid monomers which, in addition to norbornenyl or norbornadienyl groups, also have (meth)acrylate, vinyl, allyl, allyl ether, vinyl ether, epoxy or styryl groups. These monomers can be polymerized by different mechanisms, with the result that a multistage polymerization, the combination of different polymerization mechanisms or the synthesis of polymerizable polymers is possible.
Chan et al., Austr. J. Chem. 51 (1998) 31-35 describe the synthesis of hybrid monomers which contain both (meth)acrylamide and also (meth)acrylate groups. These monomers are intended to be suitable as crosslinkers when solubility both in organic and also in aqueous systems is required or when the presence of an easily hydrolyzable group is desired for the controlled degradation of the polymer network.
EP 1 182 033 A1 discloses materials for image recording which can contain a polymeric binder with different radically polymerizable groups.
JP 2001270856 A discloses a method for preparing N-(meth)-acryloyloxyethylacrylamides by transesterification. The method is intended to produce the desired products at high yield and purity.
WO 2010/019832 discloses amide-extended maleic acid imides which are intended to be suitable for strengthening thermally curing adhesives without impairing their heat stability. By “amide-extended” is meant compounds which contain at least one amide group in a non-terminal position of the molecule.
WO 96/24644 A1 relates to pressure-sensitive adhesives which are said to be suitable for coating articles. The adhesives can contain polyunsaturated monomers the unsaturated groups of which have different reactivities. Premature gelling is said to be prevented by the different reactivities.
WO 98/01419 discloses gels for gel electrophoresis which contain asymmetric crosslinkers. These are molecules with two differently reactive vinyl groups. By means of the reaction of the more reactive groups, linear polymer chains are to be formed first which are then crosslinked with each other via the second group, with the result that gels are formed with a microporous structure which is advantageous for the separation of biomolecules.